var app                 = require('http').createServer(handler),
    io                  = require('socket.io').listen(app),
    fs                  = require('fs'),
    mysql               = require('mysql'),
    connectionsArray    = [],
    connection          = mysql.createConnection({
        host        : 'localhost',
        user        : 'root',
        password    : 'papamama',
        database    : 'Restaurant'
    }),
    POLLING_INTERVAL = 3000,
    pollingTimer;

// If there is an error connecting to the database
connection.connect(function(err) {
  // connected! (unless `err` is set)
  console.log( err );
});

// creating the server ( localhost:8000 )
app.listen(80);

// on server started we can load our client.html page
function handler ( req, res ) {
    fs.readFile( __dirname + '/client.html' , function ( err, data ) {
        if ( err ) {
            console.log( err );
            res.writeHead(500);
            return res.end( 'Error loading client.html' );
        }
        res.writeHead( 200 );
        res.end( data );
    });
}

var pollingLoop = function () {
   
    // Doing the database query
    var query = connection.query('SELECT * FROM submission'),
        users = []; // this array will contain the result of our db query

    // resuming the connection that is paused each loop
    connection.resume();

    // setting the query listeners
    query
    .on('error', function(err) {
        // Handle error, and 'end' event will be emitted after this as well
        console.log( err );
        updateSockets( err );
       
    })
    .on('result', function( user ) {
        // it fills our array looping on each user row inside the db
        users.push( user );
    })
    .on('end',function(){
        // loop on itself only if there are sockets still connected
        if(connectionsArray.length) {
            pollingTimer = setTimeout( pollingLoop, POLLING_INTERVAL );
            connection.pause();

            updateSockets({users:users});
        }
    });

};

// creating a new websocket to keep the content updated without any AJAX request
io.sockets.on( 'connection', function ( socket ) {
   
    console.log('Number of connections:' + connectionsArray.length);
    // starting the loop only if at least there is one user connected
    if (!connectionsArray.length) {
        pollingLoop();
    }
   
    socket.on('disconnect', function () {
        var socketIndex = connectionsArray.indexOf( socket );
        console.log('socket = ' + socketIndex + ' disconnected');
        if (socketIndex >= 0) {
            connectionsArray.splice( socketIndex, 1 );
        }
    });
	socket.on('done', function(data){
		var queryStr =  "delete from submission where num = " + data;
		var query = connection.query(queryStr);
	});

    console.log( 'A new socket is connected!' );
    connectionsArray.push( socket );
   
});

var updateSockets = function ( data ) {
    // adding the time of the last update
    data.time = new Date();
    // sending new data to all the sockets connected
    connectionsArray.forEach(function( tmpSocket ){
        tmpSocket.volatile.emit( 'notification' , data );
    });
};
